<?xml version="1.0"?>

<!DOCTYPE rdf:RDF [
    <!ENTITY eg   'http://www.hpl.hp.com/semweb/2003/eg#'>
    <!ENTITY rdf  'http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
    <!ENTITY rdfs 'http://www.w3.org/2000/01/rdf-schema#'>
]>

<rdf:RDF xmlns:rdfs="&rdfs;" xmlns:rdf="&rdf;" xmlns="&eg;">

  <rdfs:Resource rdf:about="&eg;a" />

</rdf:RDF>